1. Field of the Invention
The present invention relates to a multilayer molded article with a good appearance which is used as an interior panel of an automobile or an electric appliance and a method for producing the same.
2. Description of the Related Art
Today, various molded articles of thermoplastic resins are known, on surfaces of which a skin material is laminated to increase their grade through improvement of their beauty and soft feeling.
One of the methods for producing such a multilayer molded article comprises molding an article of a thermoplastic resin by a suitable molding method such as injection molding and laminating a skin material which has been formed by, for example, a vacuum forming on the surface of the molded article using an adhesive.
Another method comprises placing a skin material on a mold for molding an article, closing the mold, injecting a mass of a molten thermoplastic resin in the closed mold to laminate the resin with the skin material, cooling the mold and then removing the molded article from the mold.
A further method comprises placing a skin material between upper and lower molds, supplying a mass of a molten thermoplastic resin in the unclosed molds, and closing the molds to integrate the resin and the skin material.
However, the above methods have following drawbacks.
When adhesive is used to adhere the skin material to the already molded article, the production steps are complicated so that the production cost increases. In addition, a solvent or a dispersant contained in the adhesive may pollute the environment.
In the method comprising injecting the resin melt in the closed mold, when the resin melt is injected in the mold, the resin at high temperature and high pressure contacts the skin material and presses the skin material strongly, so that the surface of the skin material is discolored or a design of the skin material is deformed. In a case of a skin material made of a raised fabric, the appearance is worsened since the raised fibers are laid down or oriented. In some cases, the resin melt reaches the surface of the skin material to impair the commercial value of the molded article.
When the molten thermoplastic resin is supplied in the unclosed molds in which the skin material is placed, it is possible to produce a good molded article by precisely defining a clearance between the upper and lower molds and a mold closing speed as proposed in Japanese Patent Kokai Publication No. 235613/1989 (U.S. Ser. No. 07/700,936). Depending on a kind or a quality of the skin material, the fibers may be laid down or the resin exudes on the skin material.